With the general aim of reducing energy consumption through the planet, an important focus of research has been directed to organic and polymer electroluminescent materials which have emerged as valuable alternatives to the production of incandescent light. The ever-growing interest in the research and development of OLED has been mainly motivated by their extended use in flat panel display technology.
While many research groups have oriented their studies towards white light production, finding reliable and efficient UV light sources has appeared as being of high interest in various domains, such as optical storage, photocatalysis, sterilization and disinfection, and various surgical methods or medical treatments such as ophthalmic surgery or epilepsy treatment.
Production of UV light by organic materials is much more challenging than white light (Visible) production due to the very few organic molecules known to emit in the UV with a quantum yield acceptable for the production of light-emitting devices.
Whereas inorganic material-based LED emitting in the UV are known, the latter have several disadvantages compared to their organic counterparts. These disadvantages include, but are not limited to, non-tunability of the electronic density of the corresponding material, and broad UV emission due to the crystal lattice in which the inorganic emitter is formed.
In that context, borazine materials have recently emerged as a new class of promising materials with alleged high electron and hole mobility for applications in electroluminescent devices. In particular, WO 2005/068583 discloses borazine-containing material with allegedly high hole and electron mobility and thermal stability, which can allegedly be used in one or more layers of an electroluminescent device, including OLED or PLED devices. These devices are allegedly claimed to be capable of emitting light in the UV or visible regions.
JP2005-170857 discloses a series of B,B,B″-trianthryl-N,N,N″-triarylborazine derivatives and which are capable of emitting in the UV-Visible region with fairly high quantum yields. Although their potential utility as a core framework for organic electronic device applications has been evoked, it remains that the fluorescence properties of the corresponding derivatives is mainly due to the anthracenyl moieties which may considerably reduce the potential electronic fine-tuning properties of the disclosed borazine derivatives and interfere with the fluorescence originating from the borazine ring.
Meller et al. in “Fluoralkyl- und Fluorarylborazinderivate, 1.Mitt.”, published in Monatshefte fuer Chemie (1966), 97(2), 619-32, pages 388-395, discloses merely the synthesis and IR spectra of various N-Fluoroalkyl- and B-Fluoroarylborazines, including B,B,B″-pentafluorophenyl-N,N,N″-triphenylborazine derivatives.
Without contesting advantages associated with the use of borazine derivative materials described in the art, there is still a need for new stable borazine derivatives with improved properties.